The study on
the use of cryptanalytic equipment has details on the use of IBM punch card
machines for codebreaking work, US efforts to solve the Enigma cipher machine using
statistical theory rather than the crib based approach of Bletchley Park, the
Soviet cipher machines Coleridge, Longfellow and Albatross, Japanese cipher
machines of WWII (Purple, Coral and Jade) etc

There is also
an interesting story regarding the Japanese Navy and the US
strip cipher .Apparently the Japanese were so impressed by the US strip system
that they copied it and started using it in mid 1944.

In page 148
it says: ‘JN87’s device was quite like
the American Navy's own strip cipher. The '87 had a plastic board holding
strips that had alphabets printed on both sides. There was a stock of one
hundred two-sided strips to choose from. Thirty at a time were placed in the
board, with their particular vertical and horizontal arrangement set according to
complex specifications given in a book of instructions.’

This system became
a major target of the American codebreakers and its solution required the
development and introduction of special cryptanalytic equipment.

In page 149 it says: ‘Steinhardt's Gypsy was a get-the job- done machine. It was a large,
4,000-pound stepping-switch and plugboard combination that required a central control
unit and five separate six-foot high bays. Each of the bays contained five
large plugboards. Each board was hand-wired to represent four of the JN87
strips. Because the strips were two-sided, the Gypsy plugboards were constructed
to represent eight choices.’

It would be interesting if someone
knowledgeable was able to compare the US methods of solution of the strip
cipher and the equipment they built with the German techniques and their ‘Tower
Clock’ machine.